"Google" searching your inbox is one of Gmail's highlights. With the lab feature, it even gets better:

Turn on Search Autocomplete from the Labs tab under Gmail Settings, and you'll get suggestions as you type in the search box. One of the most popular searches in Gmail is for names or email addresses, so the first kind of suggestions you'll see are contacts. Some names are not easy to remember (my last name is an excellent example!) — with this new Labs feature you can just type a couple letters and select the desired contact from the drop down list. Easy and quick as that.